Monday, September 15, 2014

Is a Software Bug Setting MINI Coopers on Fire?



In the summer of 2013, we got a call from the owner of a 2008 MINI Cooper S, an R56 model. She’d gotten in her car to go to work, and her power steering wasn’t working.  We got the car in, and found a burnt steering motor (EPS) and a damaged high power electrical connector.  We replaced the parts, checked the coding, verified that the steering worked, and sent her on her way.  We’ve replaced quite a few steering motors so this one didn’t raise any eyebrows.

A year later the pump failed again.  This time the connector actually melted enough to separate from the steering motor.  When the owner tried to plug it back in the sparks told him to back off.  MINI supplied a new motor and connector under parts warranty, and we changed them.  Once again the steering worked.  We thought it strange that the motor we changed a year ago would fail.

A month later the owner drove the car to dinner and parked it for the night at 8PM.  Twelve hours later – at 8 on a Sunday morning – a neighbor spotted smoke coming from the MINI’s cowl.  The owner opened the hood to find a fire above the new EPS steering motor.  It seemed like it had gotten hot enough to start a fire.  What was going on?

The car was examined by two forensic investigators, each representing insurance companies that might be involved in settling the claim.  The first investigator’s job was to learn whether the EPS started the fire, and if so, if there was a workmanship error in its fitment. There was no error found.  Installation of the motor is simple and straightforward.  

The second investigator built on the first investigator’s findings, in an effort to further understand the cause of the fire.  Both investigators agreed that the fire was started by an overheated EPS unit.  The question was, why would the EPS overheat and start a fire after sitting overnight?  There is no circumstance where the power steering motor should activate in a parked and locked car, 11 hours after it was parked for the night.

The EPS just sits there when the car is parked.  It draws no power at rest, and should have been at ambient temperature by late that night.

A conversation with the owner revealed that this was a pattern of failure.  The steering never failed when the car was in use.  Instead, the motors burned out while the car was parked.  The complaint was, “no steering when I got in the car,” as opposed to, “the power steering quit while I was driving.”

We began to wonder how many other MINI owners had experienced similar failures.  We searched our own service database and realized most MINI power steering failures we’d seen were “in the morning” as opposed to “while driving.” An Internet search raised quite a few more possibilities.  And we read of some troubling and unexplained fires in parked cars.





The investigation has ended – for now at least – with no definite answer.  The car’s insurance will pay off, and the owner will get a new car.  We were never able to determine what woke the car’s electronics up and caused it to start steering till it caught fire.

We were able to determine that the car slept most of the night undisturbed.  An analysis of the charge in the battery told us how much energy the steering motor had absorbed.  A calculation told us how rapidly that had to occur, to build enough heat to start a fire.  Another calculation told us how fast the steering could heat up, given the limitations of fuses and wiring.  We determined that it woke up and started trying to steer 30 minutes to an hour before catching fire.

That raised an interesting possibility.  Could the car have been woken up by radio signals, and come to life in an unexpected and destructive way?  We know the pushbutton entry system can do more than unlock the car.  So can the radio link that the BMW/MINI service and concierge people use.  Might something have come into the car through those channels?  We don’t know.  It’s an idea, but without more evidence we are stumped.


What’s your experience?  Do you know of a MINI that caught fire while parked, with no good explanation?

Robison Service has provided independent service, repair, and restoration for BMW and MINI owners all over New England for over 25 years. Our company is an authorized Bosch Car Service Center. We also service Mercedes, Jaguar, Land Rover, Porsche, and Rolls Royce and Bentley motorcars. We have flatbed transport throughout the region. We also offer pickup and delivery for cars in  Springfield, Wilbraham, Longmeadow, Agawam, Westfield, Northampton, and Amherst.

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